Fluid handling devices are becoming increasingly popular and there is an increased demand for fluid handling devices that are both portable and easy to use. Portable fluid handling devices are being used for applications such as home care, point of care testing, fuel cells, fragrance dispensers, etc. Many designs rely upon solenoid actuated valves to control the fluid flow through the fluid handling device. Unfortunately, as a fluid handling device's size decreases, the performance of the solenoid actuated valve often decreases as well. Prior art fluid handling devices that rely upon solenoid actuated valves can often suffer with decreased size, thereby limiting the valve's ability to handle high fluid pressures/flow rates. One reason for this is that the single solenoid coil of many prior art designs produces a limited magnetic flux. Therefore, often in solenoid valves that include only a single coil, the movable armature that opens and closes the fluid path typically has a smaller cross-sectional area than the cross-sectional area of the solenoid coil assembly. Therefore, in order to increase the size of the movable armature, the size of the single coil is typically also increased. However, increasing the size of the coil is in direct conflict with the desire of decreasing the overall size of the fluid handling device, and therefore, may not be possible.
One design attempt to overcome the above mentioned problems is to provide more than one solenoid coil to actuate the valve. For a given valve width, two solenoid coils can generally generate more force than a single coil provided with the same width. Such a design is provided in several prior patents. For example, U.S. Pat. No. 6,726,173 provides a micro-valve that includes a yoke with two solenoid coils slipped on the two legs of the yoke. A rotary armature is provided below the yoke and thus, below the two solenoids. The rotary armature is used to open one of two fluid ports in order to direct fluid through the valve. Another example is provided in U.S. Pat. No. 6,496,092. The '092 patent is directed towards an electromagnetic valve with two solenoid coils positioned above a movable armature. The movable armature controls the flow through the 3/2 valve.
Although both of the above examples provide a double coil design in order to increase the available magnetic flux produced by the valve, neither design optimizes the increased magnetic flux of the valve. This is because in each of the above patents, the movable armature is positioned below the two solenoid coils. As a result, the armature is relatively distant from the coils. Therefore, only a portion of the magnetic flux created by the double coil design is realized by the movable armature. Consequently, while the solenoid coils have an increased magnetic flux output compared to a single coil design, the overall performances of the valves still suffer.
The present invention overcomes this and other problems and an advance in the art is achieved. The present invention repositions the movable armature between the solenoid coils so as to increase the force acting on the armature.